1. Field of the Invention
The present invention is in the field of aquatic gliding boards, and more particularly to surfboards having a honeycomb core material.
2. Description of the Related Art
Aquatic gliding boards, such as surfboards and windsurfing boards, are traditionally made through a standard production technique in which polyurethane foam is cut to a desired shape and then encased in a fiber-reinforced plastic skin, such as fiberglass. The low-density polyurethane foam core material is used in an effort to minimize weight. However, such a core, though light, provides minimal strength to resist breakage, and traditional polyurethane foam/fiberglass surfboards are known to break easily, especially in large surf.
Further, high performance surfboard riders desire extremely lightweight surfboards. The traditional foam/fiberglass surfboard construction is at or approaching its limits with regard to reducing weight. For example, to decrease the weight of a traditional foam/fiberglass surfboard, designers typically thin the foam core or decrease the amount of fiber reinforcement used. However, these actions tend to result in a surfboard that is weak and brittle, and also decrease the surfboard's buoyancy. Eventually, the surfboard becomes fragile so as to be unreliable for high performance use. Also, if the board does not have sufficient buoyancy, it may become inappropriate for use. Thus, there are limits to weight reduction for a surfboard constructed using the traditional foam/fiberglass approach. Further, as designers approach the lower weight limits by producing thin foam boards with minimal fiberglass reinforcement, such fragile boards tend to crack and absorb water in the course of normal use. Thus, those who surf regularly often must replace multiple boards every year.
There have been several attempts to produce a durable, lightweight board, all of which have realized only limited success. For example, boards sold under the trade name, “Tuflite” incorporate a layer of high density foam under the surface of the exterior fiberglass skin to improve resistance to breaking and cracking. However, this construction method tends to produce boards that are very stiff. Many advanced surfers consider Tuflite boards to have poor performance characteristics.
U.S. Pat. No. 3,514,798 discloses surfboards made by adhering sheets of honeycomb material onto inner surfaces of top and bottom skin portions, which are connected to form a surfboard. The board has a hollow interior, as the honeycomb sheets do not extend through the full thickness of board. This approach has not been successful, as the weight savings of such construction has not been shown to be significant, and board performance has not been shown to be superior to traditional boards.
U.S. Pat. No. 5,514,017 teaches a surfboard having a honeycomb core made of Nomex®. This patent expressly teaches against using an aluminum honeycomb core, because the '017 inventor's surfboard designs would be heavier if using an aluminum honeycomb core than a foam core, and performance would thus be likely hindered. There is no discussion of shaping the honeycomb in the '017 patent, and the drawings illustrate a honeycomb that has a generally rectangular cross-section. Additionally, nowhere in the patent is it anticipated that the cross-sectional thickness along the length of the honeycomb will be varied.
To Applicant's knowledge, no honeycomb core surfboard has ever been commercially successful, as such surfboards have not been able to simultaneously increase strength, maintain or enhance performance characteristics relative to a traditional surfboard, or save weight sufficiently to justify the cost of the honeycomb construction.